Chapter 1-2

the study of the composition, structure and properties of matter and the changes it undergoes.

Chemistry

anything that has mass and occupies space.

Matter

definite shape and volume.

Solid

definite volume, takes the shape of its container

Liquid

no definite shape or volume.

Gas

an ionized gas (e.g., stars, lightning)

Plasma

forms at ultralow temperatures very near absolute zero, where atoms are almost not moving at all.

Bose-Einstein condensate (BEC)

elements and compounds.

Pure substances

uniform throughout, e.g., salt water, brass, air

homogeneous

non-uniform, e.g., sand and water, granite

heterogeneous

observed without changing composition (color, density, melting point)

Physical property

describes ability to change into new substances (flammability, rusting).

Chemical property

independent of amount (density, temperature, boiling point)

Intensive property

depends on amount (mass, volume, length).

Extensive property

solid → liquid

Melting (fusion)

liquid → solid

Freezing

liquid → gas

Vaporization (boiling/evaporation)

gas → liquid

Condensation

solid → gas

Sublimation

gas → solid

Deposition

comparing an attribute of an object with a given standard

Measurement

ALL PREFIXES

All prefixes

BIG NUMBERS

deca - 1

hecto - 2

kilo - 3

mega - 6

giga - 9

tera - 12

peta - 15

exa - 18

zetta - 21

yotta - 24

SMALL NUMBERS:

deci -1

centi -2

milli -3

micro - 6

nano -9

pico -12

femto -15

atto -18

zepto -21

yocto -24

length

1 m = 3.281 ft = 1.094 yd; 1 in = 2.54 cm; 1 ft = 12 in; 1 mi = 1.61 km (= 5280 ft)

Area

1 m² = 10.76 ft²; 1 ft² = 929 cm²; 1 hectare = 10,000 m² = 2.471 acres; 1 acre = 43,560 ft²

Volume

1 mL = 1 cm³ (cc); 1 L = 1000 mL = 1.057 qt; 1 m³ = 1000 L; 1 gal = 3.7854 L

Time

1 day = 24 h; 1 h = 60 min = 3600 s; 1 week = 7 days; 1 year = 365.25 days

Mass

1 kg = 1000 g = 2.2 lb; 1 g = 1000 mg; 1 metric ton = 1000 kg; 1 lb = 454 g

moderately accurate, sensitive to 0.01 g

Triple-beam balance

more accurate, 0.01 g to 0.0001 g

Top-loading balance

measures weight directly (in N).

Spring balance

cm scale has 10 divisions (0.1 cm each); inch scale 16 divisions (1/16 = 0.0625 in) — sensitivity about 0.01 cm

Ruler

measures internal/external diameters and depths; sensitivity 0.005 cm (more precise than a ruler).

Vernier caliper

works on the screw principle; sensitivity 0.001 mm; used for very small dimensions (e.g., wire diameter).

Micrometer caliper (screw gauge)

how closely individual measurements agree with each other (expressed as percent deviation).

Precision

how closely a measured value agrees with the true/accepted value (expressed as percent error).

Accuracy

Moving water turns turbines. Angat Hydroelectric Dam, San Roque Dam

Hydroelectric

Heat below the Earth's surface; flash steaming draws steam/water hotter than 182°C through pipes; superheated steam drives turbines and condensed water is recycled. Valencia (Negros Oriental); Makban (Laguna–Batangas).

Geothermal

Industrial-scale photovoltaic plants convert sunlight to electricity (large solar farms in sunny regions)

Solar

Moving air turns turbine blades connected to a rotor. Ilocos Norte (Bangui), Rizal, Guimaras, Aklan, Pilila.

Wind

Burning biomass boils water to make steam that drives a generator. Sources: coconut husks, sugarcane bagasse, rice husks (e.g., rice-husk plant in San Jose City, Nueva Ecija; plants in Isabela, Nueva Ecija, Rizal, Laguna, Metro Manila).

Biomass

the capacity to supply heat or do work.

Energy

force causing an object to move through a distan

Work

kinetic energy of the random motion of atoms and molecules

Thermal energy

measure of the average kinetic energy of particles

Temperature

most materials expand when heated and contract when cooled (why power lines sag in summer and bridges have expansion joints).

Thermal expansion

transfer of thermal energy between bodies because of a temperature difference; flows from hot to cold until thermal equilibrium.

Heat (Q)

when substances at different temperatures are mixed, the warmer loses heat and the cooler gains heat until both reach the same temperature: qlost = qgained.

Law of heat exchange

the matter/space chosen for study

System

everything outside the system.

Surroundings

matter + energy exchange

Open

energy only

Closed

Neither energy or matter

Isolated

q > 0 → system absorbs heat

endothermic

q < 0 → system releases heat

exothermic

measurement of heat flow accompanying chemical reactions, phase changes or physical changes. Total heat flow = heat of reaction system + heat of calorimeter: qrxn = −(qwater + qcal), qcal = Ccal ΔT.

Calorimetry

two Styrofoam cups, water, lid with thermometer hole; foam insulates, so the water absorbs essentially all the heat of the reaction; measures q p = ΔH.

Coffee-cup calorimeter (constant pressure)

sealed heavy steel “bomb” containing the sample, submerged in water in an insulated container; used for combustion; measures q v = ΔU; Ccal = heat supplied ÷ ΔT (calibration). • For an exothermic reaction the water/calorimeter warms up (q rxn negative); for an endothermic reaction it cools.

Bomb calorimeter (constant volume)

E + PV; ΔH = heat flow at constant pressure (q p ). It is an extensive property and a state function (depends only on initial and final states).

Enthalpy

heat exchanged between system and surroundings during a reaction. ΔH < 0 exothermic (feels hot); ΔH > 0 endothermic (feels cold).

Enthalpy of Reaction

Endothermic or Exothermic

ENDOTHERMIC (+)

Melting/fusion

Vaporization

Sublimation

EXOTHERMIC (-)

Freezing

Condensation

Deposition

heat absorbed by system

+

heat released

-

work done on the system

+

work done by the system

-